Industrial application of detonation processes may involve the use of explosive mixtures of various gases. When used as a combustible gas, acetylene is very dangerous to handle due to high detonability of acetylene-oxygen mixtures. Moreover, acetylene can detonate even with oxygen fully absent. It is noteworthy, too, that acetylene is more costly than such combustible gases as, for instance, natural gas or fuel gas (a mixture of propane and butane).
Use of hardly detonatable cheap combustible gases of the propane-butane type is preferable from the viewpoint of explosion hazard and economy. However, apparatus using such combustible gases feature an elongated pre-detonation portion (that of transition from slow combustion to detonation), reaching several diameters of the barrel bore, which exceeds ten- or even hundred-fold the length of the pre-detonation portion in apparatus using acetylene-oxygen mixtures. Therefore, replacing acetylene by hardly detonatable combustibles without introducing special devices to accelerate the burning-to-detonation transitional process and, consequently, without reducing the pre-detonation length, is conducive to larger dimensions of apparatus, lower capacity thereof, and higher consumption of working gases.
Known in the art is a gas detonation coating apparatus/cf. U.S. Pat. No. 3,150,828, class 239-79, 1964) comprising a barrel enclosed in a casing, a spark plug associated with the barrel through a main pipe, a powder sprayer inserted in the barrel, a buffer unit provided with gas conduits and associated with the barrel through additional pipes, and a gas supply system connected with the gas conduits of the buffer unit.
However, the amount of propane-butane and oxygen mixture being fed in the given case depends on the length of the pre-detonation portion, which results in excessive gas consumption.
Furthermore, higher gas consumption and the presence of the slow burning-to-detonation portion in the given apparatus extends the time required for one operating cycle and, consequently, reduces the detonation rate, i.e. the capacity of the apparatus.
Also, the elongated portion, transitional from slow burning to detonation, necessitates a longer barrel.